Dear Dr. Universe,
How do magnets work? Andrea, 8, Berkeley, Calif.
When I saw your question, I headed straight for the Magnetics Lab and met up with my friend John McCloy. I found out the word “magnet” comes from a Greek word for the region of modern-day Turkey we once called Magnesia. That’s where people found magnets in nature.
McCloy, an associate professor at Washington State University, reminded me that magnets are objects that have magnetic fields, which enter and exit through poles. You can think of these as the “front” and the “back” of the magnet, but normally we call them “north” and “south” poles.
These are the two ends where the magnetic force is the strongest. One way to remember this is that a compass needle points to the “north pole” of the earth, and the other end points in the opposite direction, “south.” It’s these north and south poles that allow magnets to push apart or snap quickly together.
When humans make magnets from scratch, they usually use materials from the Earth. Some of the materials we use include cobalt, iron, and nickel, or one of these mixed with other things. Some magnets are ceramic materials, like those you might find in flowerpots, which are made as powders, then mixed with glue or heated up to make the particles stick together. Even after the material cools down, it’s still not ready to be a magnet quite yet.
You can imagine a magnet as a giant crowd of people, with each person being a pole.
“When we magnetize one of these special materials, we want all the poles to line up in the same direction, like a bunch of arrows pointing the same way,” McCloy said. “It’s like getting all the people in your crowd facing the same way.”
Even though each person can’t see all the others in the crowd, each person can see those immediately around them and will line up the same way. It’s kind of like synchronized dancing, McCloy said. Once everything is going one direction, you have essentially a giant pole, which now can attract or repel smaller poles.
If you think about it, our planet is one big magnet. It’s one of the many kinds of natural magnets we know about. Plus, its magnetic field is the reason compasses work. The compass’s metal needle will line right up with the Earth’s magnetic field near the top of the planet.
Turtles, salmon, and some birds can use this magnetic field to figure out where they are on the planet by using magnets in their bodies.
Magnets are all around us. They are in headphone speakers, computers, library cards, and probably in most bankcards, too.
Before I left the lab, McCloy explained how magnets and electricity often work together. While we can use electricity to make magnets, we can also make magnets to create electricity. But we’ll get into that another time.